Cushion, method of and apparatus for molding a cushion for a respiratory mask

ABSTRACT

The present invention is related to a cushion ( 1 ) for a respiratory mask, to a method of manufacturing such a cushion ( 1 ) as well as to a respiratory mask including a cushion ( 1 ) and an apparatus for manufacturing a cushion ( 1 ) for a respiratory mask. It is particularly referred to a method of manufacturing a cushion ( 1 ) for a respiratory mask, comprising the steps of providing a mold comprising at least two mold halves ( 11, 13 ) and at least one core ( 12 ) therein, closing the mold, injecting a first material into the mold to form the cushion ( 1 ), wherein the core ( 12 ) is enclosed by the cushion ( 1 ) thereby forming at least one cavity ( 4 ), opening the mold, removing the core ( 12 ) from the cushion ( 1 ) to provide the at least one cavity within the cushion ( 1 ), and sealing the cavity ( 4 ).

This application is a continuation of U.S. application Ser. No.12/737,538, filed Apr. 11, 2011, which is the U.S. national phase ofInternational Application No. PCT/EP2009/005325, filed Jul. 22, 2009,which designated the U.S. and claims priority to EP Application No.08160921.6, filed Jul. 22, 2008, the entire contents of each of whichare hereby incorporated by reference.

The present invention is related to a cushion for a respiratory mask, toa method of manufacturing such a cushion as well as to a respiratorymask including a cushion and an apparatus for manufacturing a cushionfor a respiratory mask.

Respiratory masks are widely used in the medical and therapeuticalsectors. One important employment of respiratory or breathing masksrelates to treatment of sleep-related respiratory disorders, inparticular of obstructive sleep apnea (OSA). Patients suffering from OSAare often supplied with breathable gas at a continuous positive airwaypressure during rest or sleep periods. This is achieved by the patientwearing a suitable breathing mask which is connected to a breathingapparatus providing breathable gas at the necessary pressure. Due to thepressure being higher than ambient pressure the obstructed airways ofthe patient are pushed open, also referred to as “pneumatic splinting”,allowing for an adequate supply of breathable gas, such as air oroxygen. Respiratory masks, also referred to as patient interface,usually cover mouth and/or nose of a patient or user.

Since this treatment often has to continue throughout the entire rest orsleep phase, the mask has to be as comforting to the patient or user aspossible and to be adapted for long-time use. Respiratory maskstherefore often comprise a cushion, e.g. a gel cushion, whose purpose itis to provide a soft and comforting contact zone or interface betweenthe skin of the patient's face and the mask. Such cushions alsoestablish a seal between the mask and the patient's skin so that themask interior is sealed from ambience. This is of relevance particularlyin the field of, e.g., CPAP or BiPAP, breathing therapy where breathablegas is supplied at elevated pressures. The provision of a tight seal andavoidance of leaks is important to achieve a reliable and predictablebreathing pressure and thus an effective therapy. These cushions need tobe soft and cushy on the one hand, yet have to provide enough stabilityand rigidity on the other hand to keep the mask in place and toestablish the required seal.

It is known to manufacture a two-component cushion comprising an outershell of a first and an interior of a second material, such as a gel.However, manufacturing of those cushions is often rather complex, timeconsuming and thus costly process. In addition, it is generally requiredto provide a biocompatible, easy to clean and hygienic patient interfaceand cushion.

There is thus a need for an improved cushion for a respiratory mask, foran improved patient interface including a cushion, for an improvedmethod of manufacturing such a cushion, and for an improved apparatusfor manufacturing a cushion for a respiratory mask.

It is an object of the present invention to provide an improved cushionfor a respiratory mask, an improved mask including a cushion, and/or animproved method and apparatus for manufacturing such mask or cushion,which preferably overcome the deficiencies of the prior art. It is, inparticular, an object that said cushion has improved characteristicsand/or is more easily and cost-efficient to manufacture. It is anotherobject of the present invention to provide an improved method of and animproved apparatus for producing a cushion for a respiratory mask.According to a further object said method shall be more simple andefficient.

These objects are achieved by the features of the independent claims.The dependent claims relate to preferred embodiments.

The present invention is, i.e., directed to a method of manufacturing acushion for a respiratory mask. The method comprises the steps ofproviding a mold comprising at least two mold halves and a core therein,closing the mold, injecting a first material into the mold to form thecushion, wherein the core is enclosed by the cushion, opening the mold,removing the core from the cushion to provide a cavity within thecushion, and sealing the cavity. According to a preferred embodiment,the cavity is filled with a filler medium before sealing.

According to a preferred embodiment the mold comprises only one core,and preferably only one core per cavity. It is furthermore preferredthat the core consists of a single part. Thus, when the core is ejectedor demolded from the cushion only one opening or orifice, preferably percavity, remains within the cushion. According to a preferred embodimentthe mold comprises two or more cores, each for providing a distinctcavity. Thus, preferably two cores, which are e.g. bent, are provided toestablish two cavities, i.e. one cavity each. The two cores preferablyprovide one cavity at each side of the cushion. In this case the cushionpreferably has two orifices, preferably at opposite sides of thecushion.

Preferably, the core is generally C-shaped or V-shaped with a roundedtip. However, other shapes do also fall within the scope of the presentinvention. For instance, the core can be semicircular, bar-shaped withbent ends or the like. The skilled person will understand that the corehas to be shaped in such a manner as to allow for a demolding from thecushion. Preferably the shape of the core is chosen such that the stepof removing the core from the cushion leaves a single orifice in thecushion. Alternatively or additionally, the shape of the core is chosenin such that the cavity provided in the cushion has an advantageousshape and/or structure leading to an improved cushion. The core doespreferably not exhibit a ring-structure and thus is not a closedstructure. Preferably, the opening or orifice is smaller than theextensions of the core wherein demolding is possible due to elastic orelongation properties of the molded cushion. These properties preferablyallow the orifice to be temporarily enlarged for demolding wherein thecushion subsequently returns to its molded shape. Preferred materialswill be discussed further below. This structure and procedure allows theprovision of a large cavity in the molded cushion while only acomparatively small hole or orifice is to be provided in the cushion,particularly suitable for subsequent easy and advantageous filling andsealing. Preferably, the preferably C-shaped core is of large dimensionswhile the hole is of small, preferably substantially rectangular,dimensions. As will be discussed further below, the relevant andcomparable dimensions (width, length) of the orifice are in the range ofabout 1/1.5 to 1/8 and preferably between about 1/2 to 1/6 of the core'srespective largest dimension (largest width, largest height).

The cushion to be manufactured comprises a support plane, i.e. the planewhich is supported on the patient's face once the patient is wearing therespiratory mask. It is preferred that the core is arranged in such amanner in the mold, that the cavity formed by said core extendsessentially in a plane parallel to this support plane. In other words,the contour of the preferred “C” or “V” proceeds through or in a plane,which is substantially parallel to the support plane.

According to a preferred embodiment, the core is made of tool steel, inparticular of sintered tool steel, or aluminium. The core comprising orbeing made of aluminium sintered material, such as sintered steel allowsthe provision of advantageous shapes of the core. Moreover, sinteringallows easy provision of channels inside the core, e.g., for conductingcompressed air for demolding. This particularly speeds up the productioncycle.

The core can be an integrated part of one of the mold halves. It ispreferred that the core is moveable with respect to one or both of themold halves. Preferably, the core is movably connected to one of themold halves.

It is preferred that the step of removing the core from the cushioncomprises opening the mold, displacing the core together with thecushion relative to the mold halve(s). Thus, the molded cushion is firstremoved from the mold halves and afterwards detached from the core. Thisenables a more easy demolding step. The core can be removed from thecushion by either detaching the cushion from the core or demolding thecore from the cushion. This can preferably be done automatically, e.g.by means of a robot, which is adapted to capture or grip a part orportion of the cushion in order to detach the cushion from the core orto demold the core from the cushion.

In addition or alternatively, detaching the cushion is preferablyperformed by air pressure. In one embodiment, the air pressure isprovided through the core, e.g. through air canals or conduits in thecore. Thus, the cavity formed within the cushion is inflated to acertain degree which facilitates detaching the cushion from the mold.

Once the cushion is demolded, the cavity is sealed. Preferably, sealingis performed by injecting the first material into theorifice(s)/opening(s) left behind by the removed core. It is alsopreferred to seal the cavity with a material different from the firstmaterial, preferably a material being of the same kind but a differentgrade, e.g., hardness, than the first material. One preferred examplefor a material suitable for sealing the cavity is a silicone having aShore A hardness in the range of about 5 to 20, preferably of about 10.Alternatively, the cavity is sealed by gluing an insert into theorifice. In any case, the step of sealing the cavity closes the cavity,preferably airtight, against the environment.

Alternatively or additionally, after the first injection molding stepforming the cushion, one of the mold parts is opened and the core isdemolded from the cavity while the cushion remains seated in theremaining mold part. After demolding of the core, the cavity is filled.The mold is subsequently closed and the cavity is sealed by a secondinjection molding step.

According to a preferred embodiment, the first material is or comprisesone or more of a flexible first material, e.g., a plastic or syntheticmaterial such as an elastomer material or a material comprisingelastomer components. For example, the cushion may be made of siliconesuch as liquid silicone rubber (LSR), or thermoplastic elastomer (TPE).In an embodiment, an open hollow structure may be an injection moldedskin, e.g., made of silicone, a liquid silicone rubber (LSR), plastic,or TPE.

It is preferred that the method further comprises the step of fillingthe cavity with a second material prior to sealing the cavity. Preferredexamples for the second material include a fluid, i.e., a gaseous,dispersible and/or liquid fluid, an expandable fluid, a foam, a powder,beads and/or gel. According to embodiments, a mixture of the above mediamay be used, e.g., two gels of different hardness or viscosity. Suchsecond material is preferably silicone, silicone gel, silicone foam, PUgel, PU foam, oil, and/or air. It is particularly preferred that thesecond material has a lower Shore-hardness than the first material.

Preferably, the shore hardness of the cushion element is in the range ofabout 10 to 20 Shore 000. Preferably, the second material, e.g. a gel,preferably silicone gel, has a Shore 000 hardness in the range of about10 to 20, preferably between 11 and 19, and more preferably between 12and 18, between 13 and 17, between 14 and 16, and also preferable ofabout 15. The first material preferably has a Shore A hardness in therange of about 20 to 60, preferably in the range of about 35 to 45.

According to a further preferred embodiment, the cushioning element hasa Shore 000 hardness in the range of about 45 to 90. The secondmaterial, e.g. a gel, preferably silicone gel, preferably has a Shore000 hardness in the range of about 45 to 90, preferably between about 50and 90, and more preferably between about 50 and 80, between about 60and 75, between about 50 and 70, and also preferable of between about 50and 70. The first material preferably has a Shore A hardness in therange of 20 to 60, preferably in the range of about 35 to 45.Preferably, filler materials as described in WO 2009/062265, filed 17Nov. 2008, and PCT/AU2009/000682, filed 29 May 2009, are used, which areherewith incorporated by reference.

Further preferably, the cavity is sealed by using a third material,preferably a material discussed above with regard to the first and/orsecond material. Such a third material may be provided in the form of aplastic clip or other functional means. Also preferably, the seal of thecavity or orifice is formed as a fastening or securing means forallowing fixation of the cushion to a patient interface, e.g. a maskframe. Sealing may be preferably achieved by means of a two componentinjection molding step, where a first, preferably soft, material and asecond, preferably harder material are jointly or subsequently molded tothe cushion for sealing the cavity. In such embodiment, the softermaterial advantageously provides the seal, preferably being suitable forcompensation of shrinkage of the filler medium, whereas the hardermaterial is suitable for fulfilling some function, e.g., as a securingmeans. The sealing materials can also suitably provide hapticinformation, e.g., for proper positioning or alignment of the cushionvis-à-vis a patient interface to which it is to be connected.Preferably, the seal is a dosage unit for dosing the proper amount offiller medium and/or adhesive and remains adhered to the cushion therebysealing the orifice after filling of the adhesive and/or filler medium.Preferably, the second forms, is in the form of or applies,simultaneously with sealing of the orifice, a functional means, such asa fastening means, a handling means, particularly for handling duringproduction, or the like. Such means preferably has a predeterminedbreaking point in order to allow removal and disposal prior topackaging.

According to a preferred embodiment, the rigidity and/or resiliency ofthe cushion can be adjusted by varying the thickness of the cushionwalls. Therein, varying the thickness of the cushion walls is preferablyachieved by varying the thickness of the core. Additionally oralternatively, the geometry, such as size and thickness, of the core canbe varied in order to influence the wall thickness and the like of thecavity, either along the cross section of the cavity and/or along thecircumference of the cavity or the cushion. For example, the outer wallmay be thin in specific areas whereas the inner wall is thicker. Inparticular, the inner, outer, upper and lower walls of the cavity can beinfluenced independently of one another. Alternatively or additionally,the rigidity of the cushion can be adjusted by providing ribs and/orgrooves within the inner surface of the cushion's walls defining thecavity. Therein, providing ribs and/or grooves is preferably achieved byproviding grooves and/or ribs on the surface of the core. Thisparticularly allows the provision of structures influencing the rigidityand/or resiliency of the cushion while maintaining its outer structure,e.g., smooth and homogenous. The structures are formed inside thecushion, in the cavity achieved by the core.

According to a preferred embodiment, the core is shaped to allow theprovision of longitudinal and/or transverse walls in the cavity (i.e.,longitudinal with regard to the elongate extension of the cavity alongthe cushions circumference and/or transverse thereto), which result inthe provision of multiple chambers and distinct areas in the cavity.Such chambers or areas are preferably filled with different (second)filler materials having differing characteristics. Thereby the rigidityand/or resiliency of the cushion can be advantageously influenced andadapted. In particular, the rigidity and resiliency is aligned with thesealing and comfort requirements of different regions of a wearer's oruser's skin/face on which cushion is to be placed. If multiple cavitiesare achieved by using two or more cores, each of the cavities ispreferably filled with an individual filler medium, preferably withdifferent materials having different properties.

The above measures particularly allow adjustment of the flexibility,hardness and/or elasticity of the cushion, in each cross section and/oralong at least parts of its circumference, to the patient's needs.

According to a further preferred embodiment, the core is provided withrecessed and/or protruding marks, e.g., a sign, a logo, letters, orother information, which are molded into the walls of the cavity duringmolding of the cushion. Preferably, the marks are provided on the corein such a manner that, after molding of the cushion, the sign, theletters etc. are clearly visible and legible from the outside. Thisallows an easy and reliable way of providing signs etc. onto the cushionsuitable for conveying information to the user. Such informationpreferably includes the manufacturers brand, the (trade)name of thecushion or patient interface, the size of the cushion or the patientinterface, an indication on the orientation needed to connect thecushion with a patient interface. In the latter case the interfacepreferably comprises corresponding information allowing easy and fastalignment of cushion and interface for connection to one another. Theprovision of the sign, letters or other information inside the cavityvia the core during molding is of particular advantage. The applicationof the information is achieved easily and reliably without anyadditional processing steps. Furthermore, particularly since the cavityis preferably filled with a filler medium and then sealed, theinformation is protected against the environment and will neither becontaminated nor soiled during use.

The present invention further relates to an apparatus for manufacturinga cushion for a respiratory mask, and preferably for performing themethod according to the present invention. Such apparatus preferablycomprises the features of the mold, particularly discussed in relationto the method of the present invention.

The present invention further relates to a cushion for a respiratorymask. The cushion may, in particular, be manufactured according to themethod and/or by the apparatus described above. The cushion according tothe invention comprises a sealed hollow structure, preferably ofbasically ring shape and more preferred of triangular shape, adapted tofit to a patient's face and to cover a patient's mouth and/or nose. Saidhollow structure is made of a first material, wherein the hollowstructure comprises a cavity extending only along a part of thecircumference of the, preferably triangular, structure. As discussedabove, said cavity is filled with a second material, such as, e.g., asilicone gel.

Said cavity is preferably C-shaped or V-shaped with a rounded tip.However, other shapes do also fall within the scope of the presentinvention. For instance, the cavity can be semicircular, bar-shaped withbent ends or the like. Preferably, the cavity takes the shape(s) asreferred to above when discussion the geometry of the core.

The cushion comprises a support plane, i.e. the plane which is supportedon the patient's face. It is preferred that the sealed hollow structureextends essentially in a plane parallel to this support plane. In otherwords, the contour of the “C” or “V” proceeds through a plane, which issubstantially parallel to the support plane. Thus, the filled cavity isadapted to provide sufficient stability to the structure of the cushion.

According to a preferred embodiment, the opening of the “C” or “V” isadapted for positioning at the ridge of a patient's nose. In other wordsthe cavity does not extend to a region of the cushion which is designedto be placed over the ridge of a patient's nose. It is thus preferred,that the contour of the “C” or “V” essentially surrounds the nostrilsand/or the mouth of a patient using the cushion.

As discussed above, the first material comprises preferably silicone orpolysiloxane. It is further preferred that the cavity is filled with asecond material. As also referred to above, preferred examples for thesecond material are beads, fluids, foams, gels, liquids and/or gases aswell as mixtures thereof. It is particularly preferred that the secondmaterial has a lower Shore-hardness than the first material.

In the following there will be discussed further preferred embodimentsof the present invention which are to be seen as both alternative andadditional embodiments, referred to as aspects:

-   -   1. Method of manufacturing a cushion for a respiratory mask,        comprising the steps of providing a mold comprising at least two        mold halves and at least one core therein, closing the mold,        injecting a first material into the mold to form the cushion,        wherein the core is enclosed by the cushion thereby forming at        least one cavity, opening the mold, removing the core from the        cushion to provide the at least one cavity within the cushion,        and sealing the cavity.    -   2. Method according to aspect 1, wherein the mold comprises one        core per cavity to be molded, and preferably only one core.    -   3. Method according to aspect 1 or 2, wherein the core consists        of a single part and is, preferably integrally, connected to a        handling member.    -   4. Method according to any one of the preceding aspects, wherein        the core is C-shaped.    -   5. Method according to any one of the preceding aspects, wherein        the core is an integrated part of one of the mold halves, and        preferably comprises a handling member.    -   6. Method according to any one of the preceding aspects, wherein        the core is moveable with respect to one or both or all of the        mold halves.    -   7. Method according to any one of the preceding aspects, wherein        the core is made of steel, sintered steel, aluminium and/or        sintered aluminium.    -   8. Method according to any one of the preceding aspects, wherein        the step of removing the core from the cushion comprises        displacing the core together with the cushion relative to the        mold halves.    -   9. Method according to any one of the preceding aspects, wherein        the step of removing the core from the cushion comprises        detaching or demolding the cushion from the core.    -   10. Method according to aspect 9, wherein detaching the cushion        is performed by air pressure.    -   11. Method according to aspect 10, wherein the air pressure is        provided through the core and preferably the handling member.    -   12. Method according to any one of the preceding aspects,        wherein the step of removing the core from the cushion leaves a        single orifice in the cushion.    -   13. Method according to any one of the preceding aspects,        wherein the cavity is sealed by injecting the first material or        a similar material into or onto the orifice, and/or preferably        by overmolding.    -   14. Method according to any one of aspects 1 to 12, wherein the        cavity is sealed by gluing an insert into or a patch over the        orifice.    -   15. Method according to any one of the preceding aspects,        wherein the cavity is closed after removal of the core and        subsequently the cavity is sealed by overmolding a third        material, said third material preferably corresponding to the        first material.    -   16. Method according to any one of the preceding aspects,        wherein the first material comprises silicone.    -   17. Method according to any one of the preceding aspects,        further comprising the step of filling the cavity with a second        material prior to sealing the cavity.    -   18. Method according to any one of the preceding aspects,        wherein the second material is one or a combination of: foam,        gel, liquid, gas, beads, wherein these preferably comprise        silicone.    -   19. Method according to any one of the preceding aspects,        wherein the rigidity of the cushion can be adjusted by varying        the thickness of the cushion wall(s).    -   20. Method according to any one of the preceding aspects,        wherein the rigidity of the cushion can be adjusted by providing        ribs and/or grooves on/within the inner surface of the cushion,        i.e., the surfaces of the cushion forming the inner cavity        walls.    -   21. Method according to any one of the preceding aspects,        wherein varying the thickness and/or providing ribs and/or        grooves is achieved by varying the thickness of the core and/or        by providing structures such as grooves and/or ribs on the        surface of the core.    -   22. Method according to any one of the preceding aspects,        wherein there are provided two or more horizontal or        longitudinal cavities which are separated by one ore more        horizontal walls or membranes, and/or there are provided two ore        more vertical or transverse cavities or pockets which are        separated by walls or membranes extending substantially        vertically.    -   23. Method according to aspect 22, wherein there is preferably        provided one core for each cavity, wherein the core preferably        comprises one or more slits which allow molding of the wall(s)        or membrane(s) separating different cavities or pockets.    -   24. Method according to any one of the preceding aspects,        wherein the width and length of the orifice is about 1/1.5 to        1/8 and preferably 1/2 to 1/6 of the corresponding maximum        dimension of the core, and/or wherein the size of the core and        of the orifice is such that upon demolding the opening of the        orifice is elongated by preferably about 50% to 700% and        preferably by about 100% to 500% in width and/or length        direction.    -   25. Cushion for a respiratory mask, in particular a cushion        manufactured according to the method of any one of aspects 1 to        24, the cushion comprising a sealed hollow basically ring like        structure adapted to fit to over a patient's nose and made of a        first material, wherein the hollow structure comprises at least        one and preferably only one cavity extending only along a part        of the circumference of the cushion.    -   26. Cushion according to aspect 25, wherein the cavity is        C-shaped.    -   27. Cushion according to aspect 26, wherein the opening of the        “C” is adapted for positioning at the ridge of a patient's nose.    -   28. Cushion according to any one of aspects 25 to 27, wherein        the first material comprises silicone.    -   29. Cushion according to any one of aspects 25 to 28, wherein        the cavity is filled with one or a combination of: foam, gel,        liquid, gas, and/or beads wherein each of these preferably        comprises silicone.    -   30. Cushion according to any one of aspects 25 to 29, wherein        the cushion comprises a varying rigidity due to varying the        thickness of the cushion wall(s) and/or by providing ribs,        grooves and/or further structures on/within the inner surface of        the cushion, i.e., the surfaces of the cushion forming the inner        cavity walls.    -   31. Cushion according to any one of aspects 25 to 30, wherein        the cushion comprises two or more horizontal or longitudinal        cavities which are separated by one ore more horizontal walls or        membranes, and/or there are provided two ore more vertical or        transverse cavities or pockets which are separated by walls or        membranes extending substantially vertically.    -   32. Cushion according to any one of aspects 25 to 31, wherein        the dimension of the orifice are preferably in the range of        about 20 to 50 mm in width direction and of about 3 to 10 mm in        length direction, and wherein the maximum dimension of the core        in width direction is in the range of about 70 to 100 mm and of        about 30 to 50 mm in height direction.    -   33. Apparatus for manufacturing a cushion for a respiratory        mask, preferably according to any one aspects 25 to 32, and        preferably according to a method of any one of aspects 1 to 24,        comprising at least two mold parts and a core, which is        preferably C-Shaped, being connected to a handling member being        moveable with respect to at least one of the mold parts.

Preferred embodiments of the present invention are described below withrespect to the following figures.

FIG. 1 FIG. 1A (shaded) and FIG. 1B (line drawing) show a perspectiveview of a preferred embodiment of a cushion according to the presentinvention.

FIG. 2 FIG. 2A (shaded) and FIG. 2B (line drawing) show a plan view ofthe cushion of FIG. 1.

FIG. 3 FIG. 3A (shaded) and FIG. 3B (line drawing) show a sectional viewof the cushion of FIG. 1.

FIG. 4 FIGS. 4A and 4B show another sectional view of the cushion ofFIG. 1.

FIG. 5 FIG. 5A (shaded) and FIG. 5B (line drawing) show anothersectional view of the cushion of FIG. 1; FIG. 5C shows a detail of FIG.5B.

FIG. 6 schematically illustrates the method of manufacturing accordingto the present invention.

FIG. 1 (FIGS. 1A and 1B) show a perspective view of a preferredembodiment of a cushion 1 according to the present invention. Thecushion 1 has a generally tube like circular or triangular shape with anopening 25 to receive a patient's nose and/or mouth. The tip 2 of thetriangle is designed to be placed over the ridge of a patient's nose. Atthe base of the triangle, the cushion 1 comprises an orifice 3. Thisopening or orifice 3 is caused by the core used for creating a hollowcavity inside the cushion. The core was removed from the cushion afterthe molding process. In a later manufacturing step said orifice 3 may beclosed, e.g. by injection-molding or gluing an insert into or a patchover the orifice. According to a further preferred method the orifice isclosed by another injection molding step. Thus, a sealed cavity, whichis not visible in FIG. 1, remains. FIG. 2 shows a plan view of thecushion of FIG. 1. FIGS. 1 and 2 show a view onto the cushion's sidewhich is to be connected with a patient interface or face mask.Preferably, the exact one or at least one orifice 3 is not provided inthe cushions side which is to contact a wearer's face. More preferably,orifice 3 is provided on the cushion's side to be connected to a patientinterface, e.g. a mask shell or frame. This side may be opposite to thecushion's contact area, i.e., the area of the cushion to contact awearer's face.

Of course, the general shape of the cushion 1 may deviate from thetriangular shape shown in FIG. 1 and may be, e.g., round or oval or mayhave any other suitable shape. The shape of the cushion 1 is onlyconstrained by its purpose, namely to fit to a patient's face.Preferably, the cushion fits over a patient's nose and/or mouth.

As can be seen in FIGS. 1 and 2, the orifice 3 is preferably arrangedopposite to the cushions tip 2. Preferably, cushion 1 has mirrorsymmetry or is substantially mirror symmetric with regard tolongitudinal axis A. Longitudinal axis A preferably runs through tip 2of cushion 1. Orifice 3 is preferably also arranged symmetrically withregard to axis A.

The side of the cushion 3 to be connected to the patient interface suchas a face mask or mask frame (not shown) is preferably adapted to bemechanically connected to such patient interface. Preferably, thecushion comprises connection means such as protrusions, depressions,hooks, grooves, undercuts, openings, pins and/or the like in order toallow such, preferably releasable, connection. The provision of integralfastening, handling and/or connection means allows the cushion to besecured to a breathing mask or a mask frame advantageously givingstructural strength to the cushion by means of the mask frame. Itfurthermore allows easy replacement and exchangeability of aninterface's cushion upon wear or contamination. Also, easy handling ofthe cushion, either during production or subsequently by the user, isachieved.

FIG. 3 shows a sectional view of the cushion of FIG. 1 about along theaxis C-C shown in FIG. 4. In the sectional view of FIG. 3 the cavity 4within the cushion 1 becomes visible. The cavity 4 extends along aportion of the circumference of the triangular cushion only: At the tip2 of the triangle, i.e. proximate the patient's nose, the cavity ispreferably omitted. Of course, the fraction of the circumference, inwhich the cavity is omitted may vary. The cavity 4 may, e.g., be muchsmaller (narrower and/or shallower) than the one shown in FIG. 3. Forexample, the cavity 4 may extend over one half, two third, three quarteror four fifth of the circumference of the cushion. As referred to above,the cushion is adapted to cover a wearer's nose and or mouth and is thussubstantially ring shaped, e.g. triangular. It is however preferred thatthe cavity extends over most of the circumference, i.e. over 75 to 95%,most preferably over 80 to 90% of the circumference. According to apreferred embodiment, a cavity is only provided in defined regions alongthe cushions circumference or the cavity is only filled or filled withspecial filler in these regions. These regions preferably do notcomprise the area contacting the patient's nose, the ridge of the nose,and/or the area of the patient's upper lip.

According to FIG. 3 the cavity has the shape of a slightly deformed “C”.Depending on the overall shape of the cushion 1, the shape of the cavity4 can vary accordingly.

In the embodiment shown there is provided one cavity extending over asubstantial portion of the cushion's circumference. According to otherpreferred embodiments, there are provided two or more (horizontal)cavities which are separated by one ore more horizontal walls ormembranes. Horizontal is understood to be substantially parallel to thepaper plane of FIG. 3 or substantially perpendicular to the paper planeof FIG. 4. In this case, there is preferably provided one core for eachcavity. According to another or additional embodiment, the corecomprises one or more slits which allow molding of the wall(s) ormembrane(s) separating different cavities or pockets.

According to another preferred embodiment (not shown) there are providedtwo ore more (vertical) cavities or pockets which are separated by wallsor membranes extending substantially vertically, i.e., perpendicular tothe paper plane in FIG. 3 and substantially parallel to the paper planein FIG. 4. In this case, there is preferably provided one core for eachcavity. According to another or additional embodiment, the corecomprises one or more slits which allow molding of the wall(s) ormembrane(s) separating different cavities or pockets. Preferably, thecushion comprises both one or more horizontal cavities and one or morevertical cavities.

The cushion 1 comprises preferably silicone, TPE and/or oil. The cushioncan in particular be manufactured by injection-molding silicone into amold. It is further preferred that the cavity 4 is filled with a secondmaterial. Preferred examples for the second material are foams, gels,liquids and gases. Preferably, the second material is a silicone gel orother material discussed herein. It is particularly preferred that thesecond material has a lower Shore-hardness than the first material.Preferably, the Shore hardness of the second material lies in the rangereferred to above. Preferably, the shore hardness of the first materialvaries as discussed above. More preferred, the relation of the Shorehardness of the first and second material is such as discussed above. Ifthe cushion comprises more than one cavity, these cavities arepreferably filled with second material of different Shore hardness.Preferably, one cavity is filled with second material(s) of differentShore hardness. For example, the cavity may be filled with differentlayers of second material, wherein each layer exhibits a different Shorehardness. Preferably, such layers are horizontal layers (approximatelyparallel to the paper plane of FIG. 3).

It should be apparent from FIG. 3, that the general hardness or rigidityof the cushion 1 largely depends on the characteristics of the secondmaterial(s) filled into the cavity 4. However, it also depends on theproperties of the walls 5 a, 5 b of the cavity, i.e. the cushion frame.It is thus possible to also control the rigidity of the cushion byvarying the thickness of the cushion walls 5 a, 5 b. According to theinventive method this can be achieved by varying the thickness of thecore: A core of increased thickness used in combination with the samemold halves will lead to thinner walls 5 a, 5 b, while a thinner corewill result in thicker walls 5 a, 5 b. Alternatively or additionally,the rigidity of the cushion can be adjusted by providing ribs and/orgrooves within the inner surface of the cushion, i.e. on the surfaces ofthe wall 5 a, 5 b facing inside the cavity 4. Therein, providing ribsand/or grooves is preferably achieved by providing corresponding groovesand/or ribs on the surface of the core.

Thus, the properties of the cushion, in particular its flexibility,hardness and elasticity, can be easily adjusted by varying the thicknessof the cavity walls 5 a, 5 b, by varying the number and extension ofcavities (horizontal, vertical), and/or by varying the properties of thesecond material(s) inside the cavity/cavities. This allows a fine andexact adjustment of the cushion properties in line with the objectunderlying the present invention.

Moreover, the geometry of the cushion walls as well as of the cavity canbe achieved by providing a different core while using one and the samemold halves. Thus, the outer geometry of the cushion remains identicalwherein is inner geometry or structure is changed, thereby adjusting thecushions overall properties. This largely simplifies the process ofmanufacturing different cushions adapted for specific applications andthus reduces the production costs per unit. This also allows theprovision of a unified fastening structure to connect cushions withdifferent properties, such as sizes and hardness distribution, to patentinterfaces.

FIG. 4 shows another sectional view of the cushion of FIG. 1, takenalong line B-B in FIG. 2. 4 shows a first (or lower regarding theorientation shown in FIG. 4) cushion portion 21 which is to sealinglyand comfortably contact a user's face. This portion is also referred toas the cushion's contact portion or contact side. Preferably, suchcontact portion 21 comprises a sealing lip 6 for enhancing the sealingproperties of the mask. Such lip 6 also positively influences thewearing comfort of the cushion and its patient interface. Preferably,sealing lip 6 extends from the cushion's outer wall 5 a along thecontact portion 21 towards the inner wall 5 b of the cushion 1. When thecushion is not contacting a patient, lip 6 is preferably distanced fromthe cushion's lower wall 5 c. In use, lip 6 contacts a user's face.

Cushion 1 furthermore comprises a second (or upper regarding theorientation shown in FIG. 4) cushion portion or side 23. This side isfor being connected to a patient interface (not shown) such as a facemask. Connection side 23 preferably comprises fastening means asreferred to above (see rim 29 and groove 27) for connection or fasteningthe cushion 1 to/with a patient interface body or frame.

FIG. 5 shows another sectional view of the cushion of FIG. 1 taken alongline D-D through the tip 2 of the cushion. Since the cavity 4 does notextend along the whole circumference of the cushion 1, omitting inparticular the region proximate the patient's nose, in FIG. 5 the cavity4 is visible in the left part of the cushion only. FIG. 5 also shows theorifice 3 through which the core extends when cushion 1 is molded andwhich is preferably used for filling the cavity with second material(s).Preferably, cushion 1 is molded with handling means 33 provided at theexterior for improved handling, during use or production. Such handlingmeans can also be, as discussed above, be applied as a lid for orifice3. Furthermore, cushion 1 is preferably provided with some fasteningmeans 31 or lid means in the area of orifice 3 for improving closing andsealing of orifice 3 and/or for providing a securing means for a cushion3 to, e.g., a mask frame.

FIG. 6 schematically illustrates the method of manufacturing as well asa preferred apparatus for manufacturing according to preferredembodiments of the present invention. According to such embodiment,three mold parts 11, 12 and 13 are provided. They are moveable withrespect to each other. Thus, the mold can be opened and closed. Moldhalf 13 is designed complementary to the cushion's upper side 23 and toits inner side such as inner wall 5 b. Mold half 11 is designedcomplementary to the cushion's outer circumference and part of thecushion's lower side 21. Stamp 12 is designed complementary to theremainder of the cushion's lower side 21 and is adapted to form sealinglip 6.

Furthermore, a core 15 is provided within the mold formed by said moldparts 11, 12 and 13. The core is preferably C-shaped and mounted on orcomprises a handling member 14 such as, e.g., a rod. Preferably, core 15is substantially symmetrical with regard to axis A of the cushion to bemolded, as shown, e.g., in FIG. 2. Preferably, core 15 and member 14 areintegrally formed. Preferably, member 14 is moveably connected to moldhalf 13. Core 15 can thus be displaced with respect to the mold parts11, 12 and 13.

After closing the mold, a first material is injected into the moldthrough gate 16. The first material is cured or at least partially curedand thus a cushion 1 is formed. The core 15 is enclosed by the cushion 1and thus forms a cavity 4 therein. Handling member 14 extends throughorifice 3 to the outside of cushion 1. The mold is then opened bymoving, e.g., mold parts 11 and 12 away from mold part 13. The moveablepart 14 is then displaced with respect to mold part 13, preferablyleaving the core 15 together with the cushion 1 in a position withoutany contact to other mold parts. Now, the cushion 1 may be removed fromthe core 15. This may be achieved, e.g. by air pressure. For instance,member 14 and core 15 may comprises an air conduit for providingpressure. The cavity of the cushion 1 formed by the core 15 is thusinflated and the cushion 1 can be easily detached from the core 15.Alternatively, cushion 1 can be mechanically pulled of the core 15without the provision of air pressure.

Of course, the mold parts can be designed differently. According to apreferred embodiment only two mold parts 11, 13 are provided instead ofthe three mold parts 11, 12 and 13. According to another preferredembodiment, it is also preferred to provide one or more additionalpin(s), which are moveable with respect to mold part 13 in a mannercomparable to member 14. Thus, the cushion 1 is better supported whendisplacing the core 15 with cushion 1 from the mold part 13 and anunnecessary stretching or deforming of the cushion 1 is avoided. Thesepins preferably also serve to support the proper positioning of core 15.After molding, there will be a small hole, preferably with a diameter ofa few millimeters, in the cushion where the pin has been. These hole(s)will be sealed in the sealing step for sealing orifice 3. Preferably,the hole(s) left by the pin(s) a advantageous, such as orifice 3, inthat they allow air to escape from the cavity during filling thereof.

Demolding of the cushion 1 from the core 15 is possible due to the largedegree of elastic expansion that the first material, such as silicone orpolysiloxane, provides. Elongation or elasticity of the first materialpreferably lies in the range of about 300% to 400% after molding whenthe material is still warm. However, other comparable materials having asufficiently large degree of elastic expansion can be used instead.

Preferably, the preferably C-shaped core is of large dimensions whilethe hole is of small, preferably substantially rectangular, dimension.The ratio between the maximum width (referring to a top view andorientation according to e.g. FIG. 1) of the core and the respectivewidth of the orifice lies preferably in the range between 1/1.2 and1/2.5 and is preferably about 1/2. Alternatively or in addition, theratio between the maximum height of the core (referring to a side viewand orientation according to e.g. FIG. 4) and the respective length ofthe orifice (referring to a top view and orientation according to e.g.FIG. 1) lies preferably in the range between 1/4 to 1/8 and ispreferably about 1/6. While the above dimensions and ratios preferablyapply to the core, cavity and opening of a nasal cushion it will be wellunderstood to adapt the respective measures to apply to, e.g, a fullface cushion covering both, nose and mouth. Preferably, for such coreand/or orifice, the dimensions in the width direction increase by afactor of about 1.1 to 1.4 and preferably of about 1.2 to 1.3, thedimensions in the length direction increase by a factor of about 1.5 to1.8 and preferably of about 1.6 to 1.7, and/or the dimension in theheight direction preferably increase by a factor of about. 1 to 1.4,preferably of about 1.1 to 1.2. Reference to dimension made hereingenerally refers to the directions as mentioned in brackets above.

According to a preferred embodiment, as discussed above, if multiplehorizontal and/or vertical cavities or pockets are to be provided incushion 1, multiple cores or core parts are connected to handling member14. In such embodiment, handling member 14 preferably extends into anatrium of cavity 4 which is adjacent orifice 3. From said atrium thereextend cores or core parts to form the different cavities or differentparts of the cavity. Also with this embodiment, there is preferablyprovided only one core per cavity.

Orifice 3 is preferably adapted to allow handling member 14 to extendtherethrough and also to allow the core(s) to be withdrawn therethroughduring demolding. Preferably, orifice 3 is about 20 to 30, preferably to50 mm, preferably 30 to 50 mm, and more preferably about 35 to 40 mmwide and about 3 to 10 mm long. The shape and dimensions of orifice 3correspond to the cross section of member 14 of core 15 extendingtherethrough during molding. Orifice 3 is preferably arranged onfastening side 23 of the cushion to be molded.

Removing the core 15 from the cushion 1 leaves a cavity 4 within thecushion and at least one orifice 3, where the core 15 was connected tothe member 14. Said orifice 3 is closed in a later production step inorder to seal the cavity 4. Preferably, the cavity 4 is filled with asecond material, such as a silicone gel or foam, before the sealingstep. As discussed above, different cavities are preferably filled withdifferent second materials but may also be filled with the same materialhaving the same properties. According to a preferred embodiment, thecavity is filled with different second materials, e.g. in horizontallayers. Such different second materials can be the same basic materialbut having different hardness and elasticity properties.

According to a further preferred embodiment, the cushion 1 is molded asdiscussed above. After molding the mold is opened, e.g., by removingmold half 13. Then, the core is removed from the cavity/cavities viaorifice 3. In such case, orifice 3 may extend over the whole length ofthe cavity along the cushion's circumference. In a next step, at leastone second material is filled into the cavity/cavities. Subsequently,preferably after the mold halves have been closed again, orifice 3 isclosed by injecting a second shot of the first material. By such secondinjection the cavity is sealed. Preferably, some outer structures of themask are provided, e.g., as fastening means such as rim 29 and/or groove27. Said groove 27 may be adapted as a handling member, e.g., to be usedin an automatic demolding step. For example, a robot may grip thecushion making use of said groove 27 in order to detach the cushion fromthe core.

As referred to above, core 15 can be provided with structures such asgrooves, slits, rims, depressions, allowing to influence both thegeometry of the cavity and the geometry of the cushion walls. Thereby,and particularly in combination with a specific choice of the propertiesof first and/or second material, the cushion properties can beadvantageously influenced and adjusted. In particular, the inventionallows such adjustment without changing the outer dimensions of thecushion and particularly its fastening portion. Thus, the patientinterface to which the cushion has to be secured and its fasteningstructure can remain unchanged. The same applies to the mold parts 11,12, 13 forming the outer dimension of the cushion. These do not have tobe changed or replaced together with the core.

The method according to the present invention is advantageous over theprior art since it, i.e., allows for an easy and well-controlledproduction of cushions for respiratory masks. In particular, the methodcan be easily automated. One reason for this is the fact that a singlecore is used, which can be easily placed within the mold correctly andsimply removed from the cushion after curing. Preferably, even thedemolding of the core can be automated. During molding and demolding thecore is maintained inside the mold and connected to one of the moldhalves. Thus, the temperature of the core can be better maintained andcontrolled, which is important in terms of reproducibility.

A further advantage of the inventive method is the cost-efficientcontrol the rigidity, resilience and flexibility of the cushion by, e.g,varying the thickness of the cushion walls and the dimension of thecavity. As can be taken from FIG. 6 a core 15 of increased thicknessused in combination with the same mold parts 11, 12 and 13 will lead tothinner walls 5 a, 5 b, while a thinner core 15 will result in thickerwalls 5 a, 5 b. The same applies to the core's extensions in thevertical direction of FIG. 6. Alternatively or additionally, therigidity of the cushion 17 can be adjusted by providing ribs and/orgrooves within the inner surface of the cushion, i.e. on the surfaces ofthe wall 5 a, 5 b facing inside the cavity. Therein, providing ribsand/or grooves is preferably achieved by providing grooves and/or ribson the surface of the core 15.

Thus, the properties of the cushion, in particular its flexibility andelasticity, can be easily adjusted by providing different cores whileusing one and the same mold parts and leaving the remainder geometry ofthe cushion unchanged. This largely simplifies the process ofmanufacturing different cushions adapted for specific applications andthus reduces the production costs per unit. Manufacturing of the cushioncan thus be automated. Alone the core of the mold allows beneficialmanufacturing of an adjusted and improved cushion. The integral natureof the core, particularly in combination with the handling member,allows omitting manual intervention of handling, allows predefined andrepeatable position of the core, and the core to substantially maintaina temperature equilibrium with the mold while the mold is opened. Thepresent invention thus provides for an improved, efficient, effectiveand reliable method for molding cushions, a cushion and a device formolding cushions.

1. Method of manufacturing a cushion (1) for a respiratory mask,comprising the steps of providing a mold comprising at least two moldhalves (11, 12, 13) and at least one core (15) therein, closing themold, injecting a first material into the mold to form the cushion (1),wherein the core (15) is enclosed by the cushion (1) thereby forming atleast one cavity (4), opening the mold, removing the core (15) from thecushion (1) to provide the at least one cavity (4) within the cushion(1), and sealing the cavity (4), wherein the core (15) is C-shaped. 2.Method according to claim 1, wherein the step of removing the core (15)from the cushion (1) comprises displacing the care (15) together withthe cushion (1) relative to the mold halves (11, 12, 13).
 3. Methodaccording to claim 1, wherein the step of removing the core (15) fromthe cushion (1) leaves a single orifice (3) in the cushion.
 4. Methodaccording to claim 1, wherein the cavity (4) is sealed by injecting thefirst material into the orifice (3), by gluing an insert into or a patchover the orifice (3) and/or by overmolding the cushion (1) including theorifice (3).
 5. Method according to claim 1, further comprising the stepof filling the cavity (4) with a second material prior to scaling thecavity.
 6. Method according to claim 5, wherein the second material isone or a combination of foam, gel, liquid, gas, beads, wherein thesecond material preferably comprises silicone.
 7. Method according toclaim 1, wherein the rigidity of the cushion (1) can be adjusted byvarying the thickness and/or structure of the cushion wall(s) (5) alongtheir cross section and/or circumference.
 8. Method according to claim1, wherein the rigidity of the cushion (1) can be adjusted by providingribs and/or grooves on/within the inner surface of the cushion (1),i.e., the surfaces of the cushion forming the inner cavity walls (5). 9.Method according to claim 1, wherein varying the thickness and/orproviding ribs and/or grooves is achieved by varying the thickness ofthe core (15) and/or by providing structures such as grooves and/or ribson the surface of the core (15).
 10. Method according to claim 1,wherein there are provided two or more horizontal or longitudinalcavities (4) which axe separated by one ore more horizontal walls ormembranes, and/or there are provided two ore more vertical or transversecavities or pockets which are separated by walls or membranes extendingsubstantially vertically.
 11. Cushion for a respiratory maskmanufactured according to the method of claim 1, the cushion comprisinga sealed hollow basically ring like structure adapted to fit to over apatient's nose and made of a first material, wherein the hollowstructure comprises at least one and preferably only one C-shaped cavity(4) extending only along a part of the circumference of the cushion (1).12. Cushion according to claim 11, wherein the cushion (1) comprises avarying rigidity due to varying the thickness of the cushion wall(s) (5)and/or by providing ribs, grooves and/or further structures on/withinthe inner surface of the cushion (1), i.e., the surfaces of the cushionforming the inner cavity walls (5).
 13. Cushion according to claim 11,wherein the cushion (1) comprises two or more horizontal or longitudinalcavities (4) which are separated by one ore more horizontal walls ormembranes, and/or there are provided two ore more vertical or transversecavities or pockets which are separated by walls or membranes extendingsubstantially vertically.
 14. Cushion according to claim 11, whereinratio between width of the cavity and width of the orifice is in therange of about 1/1.5 and 1/2.5, preferably about 1/2, and/or wherein theratio between the length of the orifice and the height of the cavitylies in the range of about 1/5 to 1/7, preferably about 1/6,particularly for a nasal cushion.
 15. Apparatus for manufacturing acushion (1) for a respiratory mask according to claim 11, comprising atleast two mold parts and a C-Shaped core (15) being connected to ahandling member being moveable with respect to at least one of the moldparts.